Answer:
86%
Step-by-step explanation:
Let g represent the mean mark for the 10 girls in the class. Then the mean mark for the class was ...
10g +20(62%) = 30(70%)
g = 3(.7) -2(.62) . . . . . . . . . divide by 10 and subtract 2(.62)
g = .86 = 86%
The mean mark for girls was 86%.
_____
You can do this in your head if you consider it in terms of deviations from the mean. The second equation above can be rewritten and factored as ...
g = 70% +2(70% -62%)
That is, because there are 2 boys for every girl, the girl's score is above the mean by an amount that is 2 times the amount that the boy's score is below the mean. The boys' score is below by 8%, so the girls' score is above by 16%, so is 86%.
12-4=8 which means 12-8=4 which means now you have the difference of 4 and 8+4=12 which means now you have the sum of 12
Answer:
2.99
Step-by-step explanation:
Answer:
the answer is 589.4
Step-by-step explanation:
In doing this equation you do the order of operations:
(2.1 x 104)= 218.4
(3.5 x 106)= 371
you then add the answers together to get:
218.4 + 371 = 589.4
